"""Fetch Wikipedia's 'Today's Featured Article' via the REST API feed."""
import re
from dataclasses import dataclass
from datetime import date

import httpx

from .config import settings

FEED_URL = (
    "https://{lang}.wikipedia.org/api/rest_v1/feed/featured/{year:04d}/{month:02d}/{day:02d}"
)


@dataclass
class FeaturedArticle:
    title: str
    url: str
    extract: str  # plain-text extract, HTML stripped


def _strip_html(html: str) -> str:
    text = re.sub(r"<[^>]+>", " ", html)
    text = (
        text.replace("&amp;", "&")
        .replace("&quot;", '"')
        .replace("&#39;", "'")
        .replace("&lt;", "<")
        .replace("&gt;", ">")
        .replace("&nbsp;", " ")
    )
    return re.sub(r"\s+", " ", text).strip()


def get_featured_article(day: date) -> FeaturedArticle:
    url = FEED_URL.format(
        lang=settings.wikipedia_lang, year=day.year, month=day.month, day=day.day
    )
    resp = httpx.get(
        url,
        headers={
            "User-Agent": "wiki-jokes/1.0 (daily joke generator; contact: admin@example.com)",
            "Accept": "application/json",
        },
        timeout=30,
        follow_redirects=True,
    )
    resp.raise_for_status()
    data = resp.json()

    tfa = data.get("tfa")
    if not tfa:
        raise ValueError(f"No featured article (tfa) in feed for {day.isoformat()}")

    # Prefer the REST "extracts.plain.text" if present, else the summary HTML.
    extract = ""
    extracts = tfa.get("extracts") or {}
    plain = extracts.get("plain") or {}
    if plain.get("text"):
        extract = plain["text"]
    elif tfa.get("extract"):
        extract = tfa["extract"]
    elif tfa.get("summary"):
        extract = _strip_html(tfa["summary"])

    extract = _strip_html(extract) if "<" in extract else extract
    if not extract:
        raise ValueError(f"Featured article for {day.isoformat()} has no extract text")

    # Cap the extract so the prompt stays bounded (~4000 chars).
    extract = extract[:4000]

    display = (tfa.get("displaytitle") or tfa.get("title", "Unknown article"))
    display = _strip_html(display).replace("_", " ")
    return FeaturedArticle(
        title=display,
        url=tfa.get("content_urls", {}).get("desktop", {}).get("page", url),
        extract=extract,
    )